Surgical microscopes that allow a plurality of physicians to observe an operation have come into use in recent years as surgical precision has been demanded. Also, as surgical procedures have become increasingly specialized, microscopes that are easier to use for each procedure have been provided. Such microscopes include the one discussed in Japanese Laid-Open Patent Application S56-144410, which is used mainly in neurosurgery or in ear, nose, and throat department, and the one discussed in Japanese Laid-Open Patent Application H3-80849, which is used mainly in orthopedic department and plastic surgery department.
Japanese Laid-Open Patent Application S56-144410 discloses a microscope comprising a formal observer's binocular microscope, which a surgeon (the formal observer) uses for observation, and a sub-observer's binocular microscope, which is freely-detachably attached to the side of the formal observer's binocular microscope and is used by an assistant (the sub-observer) for observation.
Japanese Laid-Open Patent Application H3-80849 discloses a microscope comprising an objective lens barrel made up of an objective lens and a variable-magnification optical system; an opposed lens barrel including a beam splitter that splits the luminous flux from the objective lens barrel into two directions; and two eyepiece lens barrels attached to the ends of the opposed lens barrel.